Taking down the Necromechs super quick. Is this intended or a bug?

[Verdanice]

My SO and myself where running vaults earlier today on the CD. Last night we had kind of stumbled upon this, but confirmed with out a doubt today. I am talking taking out the three of them in the tier three vault in under 30 seconds. In the tier 1 vault with the single necromech in under 5 seconds, with just the two of us. If I recall correctly the mechs were touted as a relatively difficult encounter. Or is this all working as intended? 

I do not want to post how here in fear this was actually unintended and it making the rounds.

I am not sure if this is even a bug or what. I have not ever submitted a bug report in any game, so I apologize if this isn't the right place.